The Role of the Lysine-Specific Histone Demethylase 6b, Kdm6b In Synapse Maturation

摘要 神经元的发育和成熟需要暂时诱导细胞特异性基因的表达。 程序。这在一定程度上是由于染色质调节机制确保正确的基因 表达的基因和错误的基因在任何给定的时间都会被抑制。而调节染色质的机制 神经元分化在发育早期已经有了很好的特征，成熟的机制决定了命运 人们对神经元的了解要少得多。染色质调节的一个例子是赖氨酸27的三甲基化 组蛋白H3，这是一个与基因抑制相关的标记，在发育早期起到防止 参与替代细胞命运决定的基因的表达。我们的实验室发现H3K27me3丢失了 在神经元成熟期间的特定位置，这表明这个标记随着时间的推移经历了动态的调节。 因此，我们提出了染色质调节剂对H3K27me3的调节可能是神经元的基础 成熟。利用一个定义明确的神经元发育模型，啮齿动物的小脑，我会 KDM6B是一种赖氨酸特异的去甲基酶，参与H3K27me3的去甲基化，在小脑中的作用 成熟。我们的实验室已经证明，小脑颗粒神经元(CGN)中KDM6B的丢失导致了一种中断 成熟的基因表达程序，其中包括许多突触基因。与此一致的是，击倒 KDM6B体内注射CGN后，突触后标志物PSD-95密度降低。因此，我 假说KDM6B通过时间诱导CGN成熟基因调控CGN突触成熟 表达程序。利用强大的遗传工具和分子生物化学的结合，我计划研究 KDM6B的缺失如何影响体内细胞自主方式的CGN突触成熟 剖析KDM6B调控CGN基因表达的机制。完成这两个目标将 定义基因表达和染色质调节的变化可以在多大程度上表现为细胞的变化 成熟的命运决定神经元。此外，这项提案将阐明KDM6B到底是如何调控基因的 来调节下游细胞的变化。

ABSTRACT The development and maturation of neurons require temporal induction of cell-specific gene expression programs. This is due in part to mechanisms of chromatin regulation that make sure the right genes are expressed and the wrong genes are repressed at any given time. While chromatin mechanisms that regulate neuronal differentiation early in development are well-characterized, the mechanisms in maturing fate-committed neurons are much less understood. One example of chromatin regulation is the trimethylation of lysine 27 on histone H3, which is a mark associated with gene repression and functions early on in development to prevent the expression of genes involved in alternative cell-fate determination. Our lab has shown that H3K27me3 is lost at specific sites during neuronal maturation, suggesting that this mark undergoes dynamic regulation over time. Thus, we raised the possibility that regulation of H3K27me3 by chromatin regulators can underlie neuronal maturation. Taking advantage of a well-defined model of neuronal development, the rodent cerebellum, I will characterize the role of Kdm6b, a lysine-specific demethylase involved in demethylating H3K27me3, in cerebellar maturation. Our lab has shown that loss of Kdm6b in cerebellar granule neurons (CGNs) results in a disruption of a mature gene expression program which includes many synaptic genes. Consistent with this, knockdown of Kdm6b in vivo in CGNs resulted in decreased density of PSD-95, a marker for the postsynapse. Thus, I hypothesize that Kdm6b regulates CGN synapse maturation through the temporal induction of this mature gene expression program. Utilizing a combination of powerful genetic tools and molecular biochemistry, I plan to study how loss of Kdm6b affects CGN synapse maturation in a cell-autonomous fashion in vivo over time, as well as dissect the mechanism by which Kdm6b regulates CGN gene expression. Completion of these two aims will define to what extent can changes in gene expression and chromatin regulation manifest as cellular changes in maturing fate-committed neurons. Additionally, this proposal will elucidate exactly how Kdm6b regulates genes to mediate downstream cellular changes.